[HBASE-24713] RS startup with FSHLog throws NPE after HBASE-21751

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.1.6
• Fix Version/s: 3.0.0-alpha-1, 2.3.1, 2.4.0, 2.2.6
• Component/s: wal
• Hadoop Flags: Reviewed
• Assignee: Gaurav Kanade
• Reporter: ramkrishna.s.vasudevan
• Created: 10/Jul/20 10:53
• Updated: 07/Aug/20 08:10
• Resolved: 03/Aug/20 04:40

Description

Every RS startup creates this NPE

[sync.1] wal.FSHLog: UNEXPECTED
java.lang.NullPointerException
        at org.apache.hadoop.hbase.regionserver.wal.FSHLog$SyncRunner.run(FSHLog.java:582)
        at java.lang.Thread.run(Thread.java:748)
2020-07-07 10:51:23,208 WARN  [regionserver/xxxxx:16020] wal.FSHLog: Failed sync-before-close but no outstanding appends; closing WALjava.lang.NullPointerException

the reason is that the Disruptor frameworks starts the Syncrunner thread but the init of the writer happens after that. A simple null check in the Syncrunner will help here .
No major damage happens though since we handle Throwable Exception. It will good to solve this.

Issue Links

• links to: GitHub Pull Request #2125
• links to: GitHub Pull Request #2133
• links to: GitHub Pull Request #2134
• links to: GitHub Pull Request #2201